JP2004317642A - Optical attenuator and light attenuator array - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize an optical attenuator and an optical attenuator array which are compact, integrated and variable in attenuation without using such large driving parts as a micrometer and an actuator. <P>SOLUTION: The optical attenuator attenuates input light and outputs as output light. The optical attenuator is provided with a substrate on one face of which a groove part is formed, a first waveguide which is so provided that the input light is inputted from one end, outputted from the other end, and the one end is fixed on the substrate and the other end is arranged on a groove part, a second waveguide which is so provided that one end is arranged on the groove part opposite to the other end of the first waveguide, and the light outputted from the first waveguide is inputted to the one end, and the other end is fixed on the substrate and output light is outputted from the other end, and a driving means which varies the position of at least one of the one end of the first waveguide and the one end of the second substrate. The input light is attenuated and outputted as output light by dislocating the positions of the other end of the first waveguide and the other end of the second waveguide which are opposite to each other by giving a driving force with the driving means to at least the one end of the first waveguide and the one end of the second waveguide. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an optical attenuator used for adjusting an optical signal strength of a DWDM (Dense Wavelength Division Multiplexing) system, an EDFA optical amplifier (erbium-doped fiber amplifier), an optical measuring device, etc. incorporated in an optical communication system. It is.
[0002]
[Prior art]
11 and 12 are views for explaining a conventional optical attenuator.
The optical attenuator shown in FIG. 11A has two optical fibers 40 and 41 installed coaxially and linearly with a narrow gap therebetween. For example, the light emitted from the core 40 a of the optical fiber 40. Enters the core 41a of the optical fiber 41 with a certain coupling efficiency.
[0003]
Then, as shown in FIG. 11B, when the optical fiber 41 is displaced by, for example, a micrometer 42 or an electromagnetically driven actuator, the amount of light incident on the core 41a of the optical fiber 41 changes. Thereby, it is possible to attenuate the input light to an arbitrary light intensity and output the light.
[0004]
The optical attenuator shown in FIG. 12A is provided with two optical fibers 50 and 51 and a mirror 52. For example, light emitted from the core 50 a of the optical fiber 50 is reflected by the mirror 52. Then, the light enters the core 51a of the optical fiber 51 with a certain coupling efficiency.
[0005]
Then, as shown in FIG. 12B, when the mirror 52 is tilted by, for example, a micrometer 53 or an electromagnetically driven actuator, the amount of light incident on the core 51a of the optical fiber 51 changes. Thereby, the input light can be attenuated to an arbitrary light intensity and output.
[0006]
[Problems to be solved by the invention]
However, such an optical attenuator with variable attenuation has the following problems.
In order to operate optical fibers and mirrors, micrometers and electromagnetically driven actuators are required, but these components are large, which is a factor that hinders the large capacity and multi-channel required for optical communication. .
[0007]
In addition, when multiple optical attenuators are integrated to handle multi-channel optical signals, each optical attenuator requires a micrometer or an electromagnetically driven actuator, etc., and the entire device becomes larger and more complex. I will.
[0008]
SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and has a small and variable attenuation optical attenuator and an optical attenuation that can be integrated without using a large driving unit such as a micrometer or an actuator. The purpose is to realize a container array.
[0009]
[Means for Solving the Problems]
According to claim 1 of the present invention, in an optical attenuator for attenuating input light and outputting the output light, a substrate having a groove formed on one surface, the input light being input from one end and being output from the other end And a first waveguide provided with one end fixed on the substrate and the other end disposed on the groove, and one end disposed opposite to the other end of the first waveguide on the groove. A second waveguide provided so that light output from the first waveguide is input from one end and the other end is fixed on the substrate, and the output light is output from the other end; and Driving means for displacing at least one of the end and one end of the second waveguide, and the driving means applies a driving force to at least one of the other end of the first waveguide and one end of the second waveguide. And the other end of the first waveguide and the second By shifting the position of the other end of the waveguide is an optical attenuator and outputs as the output light by attenuating the input light.
[0010]
According to a second aspect of the present invention, in the optical attenuator according to the first aspect, the first waveguide and the second waveguide each include a core made of Si or a Si compound and a core surrounding the core and made of Si or a Si compound. A cladding having a refractive index smaller than that of a core; and the driving unit includes a movable electrode provided on the cladding and a fixed electrode provided on a bottom of the groove. An optical attenuator characterized by an electrostatic force generated by applying a voltage between an electrode and the fixed electrode.
[0011]
According to a third aspect of the present invention, in the optical attenuator according to the first aspect, the first waveguide and the second waveguide each include a core made of Si or a Si compound and a core surrounding the core and made of Si or a Si compound. A cladding having a refractive index smaller than that of a core, wherein the driving means includes a movable electrode provided on the cladding or a bimorph and a movable electrode provided on the cladding, and the driving force is This is an optical attenuator characterized by thermal stress generated by energizing an electrode.
[0012]
According to a fourth aspect of the present invention, in the optical attenuator according to the first aspect, a fixing groove for fixing an optical fiber for connecting to the first waveguide and the second waveguide is provided on the substrate. It is a characteristic optical attenuator.
[0013]
According to a fifth aspect of the present invention, there is provided an optical attenuator array, wherein a plurality of the optical attenuators according to any one of the first to fourth aspects are provided on the same substrate.
[0014]
According to a sixth aspect of the present invention, in the optical attenuator for attenuating input light and outputting the output light, a substrate having a groove formed on one surface, the input light being input from one end, and the output being output from the other end. A waveguide from which light is output, both ends of which are fixed to the substrate and whose main body is displaceably disposed on the groove; a leakage waveguide provided at the bottom of the groove; Driving means for displacing in the direction of the wave path, and driving the waveguide by the driving means to contact the leaky waveguide and leak light in the waveguide to the leaky waveguide, An optical attenuator characterized in that the input light is attenuated according to a contact length between a waveguide and the leakage waveguide and output as the output light.
[0015]
According to a seventh aspect of the present invention, in the optical attenuator according to the sixth aspect, the waveguide and the leakage waveguide are made of Si or a Si compound, and the driving means is a movable member provided on the waveguide. An electrode and a fixed electrode provided below the leakage waveguide, wherein the driving force is an electrostatic force generated by applying a voltage between the movable electrode and the fixed electrode. It is a characteristic optical attenuator.
[0016]
According to an eighth aspect of the present invention, in the optical attenuator according to the sixth aspect, the waveguide and the leakage waveguide are made of Si or a Si compound, and the driving means is a movable member provided on the waveguide. An optical attenuator comprising an electrode or a bimorph and a movable electrode provided on the waveguide, wherein the driving force is a thermal stress generated by applying a current to the movable electrode.
[0017]
According to a ninth aspect of the present invention, in the optical attenuator according to the sixth aspect, a fixing groove for fixing an optical fiber for connecting to the first waveguide and the second waveguide is provided on the substrate. It is a characteristic optical attenuator.
[0018]
A tenth aspect of the present invention is an optical attenuator array, wherein a plurality of the optical attenuators according to any one of the sixth to ninth aspects are provided on the same substrate.
[0019]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram showing a configuration of an optical attenuator according to the present invention. In FIG. 1, an optical attenuator is provided with a first waveguide 2, a second waveguide 3, and optical fibers 4 and 5 on a Si substrate 1. It is configured.
[0020]
The first waveguide 2 includes a core 2a and a cladding 2b surrounding the core 2a and having a smaller refractive index than the core 2a. Similarly, the second waveguide 3 surrounds the core 3a and the core 3a and And a cladding 3b having a small refractive index.
[0021]
For example, when the refractive index of the cores 2a and 3a is n3 and the refractive index of the claddings 2b and 3b is n4, for example, n4 is smaller than n3 by about 0.1% to 1% (for example, n3 = 1.5, n4 = 1.48) In this case, light is confined in the cores 2a and 3a, and the first waveguide 2 and the second waveguide 3 function as optical waveguides.
[0022]
The material of the cores 2a, 3a and the claddings 2b, 3b is, for example, single crystal Si (refractive index: about 3.4), polycrystalline Si (refractive index: about 3.4), or SiN (refractive index: about 2.0). It is selected from Si compounds, and the value of the refractive index of these materials can be adjusted by controlling the film forming conditions so as to be the refractive index for functioning as an optical waveguide.
[0023]
A groove 1a is formed in the Si substrate 1 by etching. One end 2c of the first waveguide 2 is fixed to an edge of the groove 1a on the Si substrate 1, and the other end 2d is formed on the groove 1a. The first waveguide 2 is arranged and fixed to the Si substrate 1 in a cantilever manner.
[0024]
One end 3c of the second waveguide 3 is disposed opposite to the end 2d of the first waveguide 2 on the groove 1a, and the other end 3d is fixed to the edge of the groove 1a on the Si substrate 1. The second waveguide 3 is fixed to the Si substrate 1 in a cantilever manner.
[0025]
The fixed electrode 6 is formed at the bottom of the groove 1a facing the second waveguide 3 by, for example, doping impurities at a high concentration.
On the cladding 3b of the second waveguide 3, a movable electrode 7 is formed by patterning a metal such as aluminum, gold, chromium, titanium, and platinum.
When the clad 3b of the second waveguide 3 is made of Si, the movable electrode may be formed by doping the clad 3b with an impurity at a high concentration.
[0026]
For example, V-shaped fixing grooves 1b and 1c are formed on the edge of the Si substrate 1 where the first waveguide 2 and the second waveguide 3 are fixed, and optical fibers are respectively formed in the fixing grooves 1b and 1c. 4 and 5 are fixed.
The optical fibers 4 and 5 are composed of cores 4a and 5a and clads 4b and 5c, respectively.
[0027]
In this case, the fixing groove 1b is formed by fixing the optical fiber 4 in the fixing groove 1b so that the core 4a of the optical fiber 4 and the core 2a of the first waveguide 2 are coaxially aligned. The shape such as the depth and the V-shaped angle is designed and formed in advance according to the diameter.
[0028]
Similarly, by fixing the optical fiber 5 in the fixing groove 1c, the cladding 5b of the optical fiber 5 is fixed so that the core 5a of the optical fiber 5 and the core 3a of the second waveguide 3 are coaxially aligned. The shape such as depth, V-shape angle, etc. is designed and formed in accordance with the diameter of.
[0029]
Next, the operation of the optical attenuator shown in FIG. 1 will be described.
The input light input from one end of the optical fiber 4 passes through the first waveguide 2 connected to the other end of the optical fiber 4, and further, the second waveguide is disposed to face the first waveguide 2 with a predetermined coupling efficiency. 3 and is output as output light from an optical fiber 5 connected to the second waveguide 3.
[0030]
Then, as shown in FIG. 2, when a driving voltage is applied between the fixed electrode 6 and the movable electrode 7, an electrostatic attraction is applied between the two electrodes, and the end 3c of the second waveguide 3 moves in the direction of the groove 1a. Displace.
As a result, the positions of the end 2d of the first waveguide 2 and the end 3c of the second waveguide 3 which are opposed to each other are shifted, so that the efficiency of optical coupling from the first waveguide 2 to the second waveguide 3 is reduced. The input light is attenuated and output as output light.
[0031]
Then, by controlling the magnitude of the driving voltage to control the magnitude of the displacement between the end 2d of the first waveguide 2 and the end 3c of the second waveguide 3, the attenuation of the input light is controlled. can do.
[0032]
When operating such an optical attenuator, a micrometer, an electromagnetically driven actuator, or the like is not required, so that the optical attenuator can be reduced in size.
[0033]
Next, another embodiment of the present invention will be described.
In the following drawings, the same parts as those in FIG. 1 are denoted by the same reference numerals, and the description thereof will be appropriately omitted.
FIG. 3 is a cross-sectional view illustrating a configuration of an optical attenuator using thermal stress due to a bimetal effect as a driving force.
[0034]
3, the optical attenuator is provided with a bimorph 8 using a metal or a Si material on the cladding 3b of the second waveguide 3 of the optical attenuator shown in FIG. A movable electrode 7 having a different expansion coefficient is provided, and a fixed electrode is removed.
The movable electrode 7 may be provided directly on the clad 3b without providing the bimorph 8.
[0035]
The bimorph has a property of being deformed due to a difference in the coefficient of thermal expansion of the structure, for example, when current is applied to the structure.
[0036]
In FIG. 3, when a current is applied to the movable electrode 7, the temperature of the movable electrode 7 rises, and a thermal stress is generated between the movable electrode 7 and the clad 3b when the bimorph 8 is not provided. Then, as shown in FIG. 4, the second waveguide 3 is displaced in the direction of the groove 1a or in the direction opposite to the groove 1a.
[0037]
As a result, the position of the end 2d of the first waveguide 2 and the position of the end 3c of the second waveguide 3 which are opposed to each other are shifted, so that the optical coupling efficiency from the first waveguide 2 to the second waveguide 3 is reduced, The input light is attenuated and output as output light.
[0038]
By controlling the magnitude of the driving power to control the magnitude of the displacement between the end 2d of the first waveguide 2 and the end 3c of the second waveguide 3, the attenuation of the input light is reduced. Can be controlled.
[0039]
FIG. 5 is a cross-sectional view showing a configuration of an optical attenuator configured to obtain an optical attenuation effect by leaking light.
In FIG. 5, the optical attenuator is configured by providing a waveguide 9, a leakage waveguide 10, and optical fibers 4 and 5 on a Si substrate 1.
[0040]
One end 9a and the other end 9b of the waveguide 9 are fixed to the edge of the groove 1a on the Si substrate 1, and the waveguide 9 is fixed to the Si substrate 1 in a doubly supported manner.
[0041]
The waveguide 9 is made of a Si compound such as, for example, single-crystal Si (refractive index: about 3.4), polycrystalline Si (refractive index: about 3.4), or SiN (refractive index: about 2.0).
For example, when the core is made of Si (refractive index = 3.4), the air filling the groove 1a has a refractive index of 1 and is smaller than the refractive index of the waveguide 9, so that light is confined in the waveguide 9. Function as an optical waveguide.
[0042]
A leakage waveguide 10 made of, for example, a Si compound such as SiO ₂ is formed at the bottom of the groove 1 a facing the waveguide 9.
The leakage waveguide 10 can be formed by using, for example, an insulating layer provided between the Si substrate of the SOI substrate and the Si active layer.
[0043]
A fixed electrode 11 is formed under the leakage waveguide 10 by, for example, doping impurities at a high concentration, and a metal such as aluminum, gold, chromium, titanium, and platinum is patterned above the waveguide 9. Thus, the movable electrode 12 is formed.
When the waveguide 9 is made of Si, the movable electrode may be formed by doping the waveguide 9 with an impurity at a high concentration.
[0044]
The optical fibers 4 and 5 are fixed to the fixing grooves 1b and 1c, respectively, such that the cores 4a and 5a and the waveguide 9 are arranged coaxially.
[0045]
Next, the operation of the optical attenuator shown in FIG. 5 will be described.
The input light input to one end of the optical fiber 4 passes through the waveguide 9 in which one end 9 a is connected to the other end of the optical fiber 4, and is connected to the other end 9 b of the waveguide 9. The light is output from the optical fiber 5 as output light.
[0046]
Then, as shown in FIG. 6, when a driving voltage is applied between the fixed electrode 11 and the movable electrode 12, an electrostatic attraction is applied between the two electrodes, and the waveguide 9 is displaced in the direction of the groove 1a to cause the leakage conduction. It contacts the wave path 10.
[0047]
When the waveguide 9 and the leakage waveguide 10 come into contact with each other, part of the light in the waveguide 9 leaks to the leakage waveguide 10, so that the light in the waveguide 9 is attenuated and output as output light. You.
[0048]
The amount of light leaking into the leakage waveguide 10 increases as the contact length between the waveguide 9 and the leakage waveguide 10 increases, and the amount of output light decreases.
Therefore, by controlling the drive voltage to control the contact length between the waveguide 9 and the leakage waveguide 10, the attenuation of the input light can be controlled.
[0049]
FIG. 7 is a cross-sectional view showing a configuration of an optical attenuator in which thermal stress due to the bimetal effect is used as a driving force to leak light and obtain an optical attenuation effect.
Note that the same parts as those in FIG. 5 are denoted by the same reference numerals, and description thereof will be omitted as appropriate.
[0050]
7, the optical attenuator is provided with a bimorph 13 using a metal or a Si material on the waveguide 9 of the optical attenuator shown in FIG. An electrode 12 is provided, and the fixed electrode is removed.
The movable electrode 12 may be provided directly on the waveguide 9 without providing the bimorph 13.
[0051]
In FIG. 7, when a current is applied to the movable electrode 12, the temperature of the movable electrode 12 rises, and thermal stress is generated between the movable electrode 12 and the waveguide 9 when the bimorph 13 is not provided. 8 and the waveguide 9 is displaced in the direction of the groove 1a as shown in FIG.
[0052]
Then, by bringing the waveguide 9 into contact with the leakage waveguide 10, light leaks from the waveguide 9 to the leakage waveguide 10, so that the input light is attenuated and output as output light.
[0053]
Then, by controlling the magnitude of the driving power to control the contact length between the waveguide 9 and the leakage waveguide 10, the attenuation of the input light can be controlled.
[0054]
Next, an optical attenuator array using the above-described optical attenuator will be described.
FIG. 9 is a top view of the optical attenuator array according to the present invention, in which the optical attenuators shown in FIG. 3 are arrayed.
In the following drawings, the same parts as those in FIG. 3 are denoted by the same reference numerals, and description thereof will be omitted as appropriate.
[0055]
In FIG. 9, the optical attenuator array 20 includes a plurality of optical attenuators 21a, 21b, 21c, 21d, and 21e formed in parallel on the same Si substrate 22.
[0056]
Since the optical attenuator shown in FIG. 3 is manufactured by a semiconductor manufacturing technique, a plurality of optical attenuators are formed on a Si substrate in parallel in one manufacturing process, so that the optical attenuator array 20 shown in FIG. Can be easily produced.
[0057]
Although FIG. 9 shows an example in which the optical attenuators shown in FIG. 3 are arrayed as an example, the optical attenuators shown in FIGS. 1, 5, and 7 are also produced by a semiconductor manufacturing technique. Therefore, it is possible to similarly form an array on the same substrate.
[0058]
Further, in such an optical attenuator array, since there is no need for a micrometer or an electromagnetically driven actuator for each optical attenuator, it is possible to reduce the size of the entire apparatus.
[0059]
FIG. 10 is a configuration diagram showing an example of use of the optical attenuator array shown in FIG.
In FIG. 10, a wavelength filter 30 divides input light into optical signals of a plurality of wavelengths, and a plurality of amplifiers 31a, 31b, 31c, and 31d individually amplify the divided optical signals.
The optical signals amplified by the amplifiers 31a, 31b, 31c, and 31d are input to the respective channels of the optical attenuator array 20.
[0060]
The control circuit 32 is connected to the optical attenuator array 20, and controls each optical attenuator corresponding to each channel to attenuate and output each input light so as to obtain a desired optical attenuation. .
The light amount monitor 33 is connected to the optical attenuator array 20, and monitors the light amount of the optical signal attenuated and output for each channel.
[0061]
In the field of optical communication, when it is necessary to equalize the intensity of each optical signal of multiple channels, the intensity (light intensity) of the output signal of each channel is monitored by the light intensity monitor 33, and control is performed so that the light intensity of each channel becomes equal. The circuits 32 control the individual optical attenuators of the optical attenuator array 20.
[0062]
【The invention's effect】
As described above, according to the present invention, an optical waveguide is formed in a semiconductor substrate to control the optical coupling efficiency or the amount of leaked light by electrostatic force or thermal stress. It is possible to realize an optical attenuator having a small attenuation and a variable attenuation amount that can be integrated without using a simple driving unit.
[0063]
Further, according to the present invention, since an optical attenuator is manufactured on a semiconductor substrate by a semiconductor manufacturing technology, a plurality of optical attenuators can be integrated on the same semiconductor substrate, and a large driving device such as a micrometer or an actuator can be used. It is possible to easily realize an optical attenuator array having a variable amount of attenuation without using any part.
[0064]
[Brief description of the drawings]
FIG. 1 is a sectional view showing a configuration of an optical attenuator according to the present invention.
FIG. 2 is a diagram for explaining the operation of the optical attenuator shown in FIG.
FIG. 3 is a cross-sectional view illustrating a configuration of an optical attenuator using a stress caused by a bimetal effect as a driving force.
FIG. 4 is a diagram for explaining the operation of the optical attenuator shown in FIG.
FIG. 5 is a sectional view showing a configuration of an optical attenuator configured to obtain an optical attenuation effect by leaking light.
FIG. 6 is a diagram for explaining the operation of the optical attenuator shown in FIG.
FIG. 7 is a cross-sectional view illustrating a configuration of an optical attenuator configured to obtain a light attenuating effect by leaking light using a stress caused by a bimetal effect as a driving force.
8 is a diagram for explaining the operation of the optical attenuator shown in FIG.
FIG. 9 is a top view showing a configuration of an optical attenuator array according to the present invention.
FIG. 10 is a diagram illustrating an example of use of an optical attenuator array.
FIG. 11 is a schematic diagram of a configuration of a conventional optical attenuator.
FIG. 12 is a schematic diagram of a configuration of a conventional optical attenuator.
[Explanation of symbols]
Reference Signs List 1 Si substrate 1a Grooves 1b, 1c Fixed groove 2 First waveguide 2a Core 2b Cladding 2c, 2d End 3 Second waveguide 3a Core 3b Cladding 3c, 3d End 4,5 Optical fiber 6 Fixed electrode 7 Working electrode 9 Conduction Waveguides 9a, 9b End 10 Leakage waveguide 11 Fixed electrode 12 Movable electrode 20 Optical attenuator array 21a, 21b, 21c, 21d, 21e Optical attenuator 22 Si substrate

Claims (10)

In an optical attenuator that attenuates input light and outputs it as output light,
A substrate having a groove formed on one surface;
A first waveguide provided such that the input light is input from one end and output from the other end and one end is fixed on the substrate and the other end is arranged on the groove portion;
One end is arranged opposite to the other end of the first waveguide on the groove, the light output from the first waveguide is input from one end, the other end is fixed on the substrate, and the output light is from the other end. A second waveguide provided to be output,
Driving means for displacing at least one of the other end of the first waveguide and one end of the second waveguide, and
The driving means applies a driving force to at least one of the other end of the first waveguide and one end of the second waveguide, and positions the other end of the first waveguide and the other end of the second waveguide facing each other. Wherein the input light is attenuated and output as the output light. The optical attenuator according to claim 1,
The first waveguide and the second waveguide are provided with a core made of Si or a Si compound and a clad surrounding the core and having a smaller refractive index than the core made of Si or a Si compound,
The driving unit includes a movable electrode provided on the clad and a fixed electrode provided on the bottom of the groove,
The optical attenuator, wherein the driving force is an electrostatic force generated by applying a voltage between the movable electrode and the fixed electrode. The optical attenuator according to claim 1,
The first waveguide and the second waveguide are provided with a core made of Si or a Si compound and a clad surrounding the core and having a smaller refractive index than the core made of Si or a Si compound,
The driving unit includes a movable electrode provided on the clad or a bimorph and a movable electrode provided on the clad,
The optical attenuator, wherein the driving force is a thermal stress generated by energizing the movable electrode. The optical attenuator according to claim 1,
An optical attenuator, wherein a fixing groove for fixing an optical fiber for connecting to the first waveguide and the second waveguide is provided in the substrate. 5. An optical attenuator array, wherein a plurality of the optical attenuators according to claim 1 are provided on the same substrate. In an optical attenuator that attenuates input light and outputs it as output light,
A substrate having a groove formed on one surface;
A waveguide in which the input light is input from one end, the output light is output from the other end, and both ends are fixed on the substrate and the main body is displaceably disposed on the groove;
A leakage waveguide provided at the bottom of the groove,
Driving means for displacing the main body of the waveguide in the direction of the leakage waveguide,
The drive unit drives the waveguide to contact the leaky waveguide to leak light in the waveguide to the leaky waveguide, according to a contact length between the waveguide and the leaky waveguide. An optical attenuator, wherein the input light is attenuated and output as the output light. The optical attenuator according to claim 6,
The waveguide and the leakage waveguide are made of Si or a Si compound,
The driving unit includes a movable electrode provided on the waveguide and a fixed electrode provided below the leakage waveguide,
The optical attenuator, wherein the driving force is an electrostatic force generated by applying a voltage between the movable electrode and the fixed electrode. The optical attenuator according to claim 6,
The waveguide and the leakage waveguide are made of Si or a Si compound,
The driving unit includes a movable electrode provided on the waveguide or a bimorph and a movable electrode provided on the waveguide,
The optical attenuator, wherein the driving force is a thermal stress generated by energizing the movable electrode. The optical attenuator according to claim 6,
An optical attenuator, wherein a fixing groove for fixing an optical fiber for connecting to the first waveguide and the second waveguide is provided in the substrate. 10. An optical attenuator array, wherein a plurality of optical attenuators according to claim 6 are provided on the same substrate.

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